An Adaptive Linearization Method for a Constraint Satisfaction Problem in Semiconductor Device Design Optimization (open access)

An Adaptive Linearization Method for a Constraint Satisfaction Problem in Semiconductor Device Design Optimization

The device optimization is a very important element in semiconductor technology advancement. Its objective is to find a design point for a semiconductor device so that the optimized design goal meets all specified constraints. As in other engineering fields, a nonlinear optimizer is often used for design optimization. One major drawback of using a nonlinear optimizer is that it can only partially explore the design space and return a local optimal solution. This dissertation provides an adaptive optimization design methodology to allow the designer to explore the design space and obtain a globally optimal solution. One key element of our method is to quickly compute the set of all feasible solutions, also called the acceptability region. We described a polytope-based representation for the acceptability region and an adaptive linearization technique for device performance model approximation. These efficiency enhancements have enabled significant speed-up in estimating acceptability regions and allow acceptability regions to be estimated for a larger class of device design tasks. Our linearization technique also provides an efficient mechanism to guarantee the global accuracy of the computed acceptability region. To visualize the acceptability region, we study the orthogonal projection of high-dimensional convex polytopes and propose an output sensitive algorithm for …
Date: May 1999
Creator: Chang, Chih-Hui, 1967-
System: The UNT Digital Library
Agent-Based Architecture for Web Deployment of Multi-Agents as Conversational Interfaces. (open access)

Agent-Based Architecture for Web Deployment of Multi-Agents as Conversational Interfaces.

Agent-based architecture explains the rationale and basis for developing agents that can interact with users through natural language query/answer patterns developed systematically using AIML (artificial intelligence mark-up language) scripts. This thesis research document also explains the architecture for VISTA (virtual interactive story-telling agents), which is used for interactive querying in educational and recreational purposes. Agents are very effective as conversational interfaces when used along side with graphical user interface (GUI) in applications and Web pages. This architecture platform can support multiple agents with or with out sharing of knowledgebase. They are very useful as chat robots for recreational purposes, customer service and educational purposes. This platform is powered by Java servlet implementation of Program D and contained in Apache Tomcat server. The AIML scripting language defined here in is a generic form of XML language and forms the knowledgebase of the bot. Animation is provided with Microsoft® Agent technology and text-to-speech support engine.
Date: May 2003
Creator: Pothuru, Ranjit Kumar
System: The UNT Digital Library
Agent Extensions for Peer-to-Peer Networks. (open access)

Agent Extensions for Peer-to-Peer Networks.

Peer-to-Peer (P2P) networks have seen tremendous growth in development and usage in recent times. This attention has brought many developments as well as new challenges to these networks. We will show that agent extensions to P2P networks offer solutions to many problems faced by P2P networks. In this research, an attempt is made to bring together JXTA P2P infrastructure and Jinni, a Prolog based agent engine to form an agent based P2P network. On top of the JXTA, we define simple Java API providing P2P services for agent programming constructs. Jinni is deployed on this JXTA network using an automated code update mechanism. Experiments are conducted on this Jinni/JXTA platform to implement a simple agent communication and data exchange protocol.
Date: December 2003
Creator: Valiveti, Kalyan
System: The UNT Digital Library
Algorithms for Efficient Utilization of Wireless Bandwidth and to Provide Quality-of-Service in Wireless Networks (open access)

Algorithms for Efficient Utilization of Wireless Bandwidth and to Provide Quality-of-Service in Wireless Networks

This thesis presents algorithms to utilize the wireless bandwidth efficiently and at the same time meet the quality of service (QoS) requirements of the users. In the proposed algorithms we present an adaptive frame structure based upon the airlink frame loss probability and control the admission of call requests into the system based upon the load on the system and the QoS requirements of the incoming call requests. The performance of the proposed algorithms is studied by developing analytical formulations and simulation experiments. Finally we present an admission control algorithm which uses an adaptive delay computation algorithm to compute the queuing delay for each class of traffic and adapts the service rate and the reliability in the estimates based upon the deviation in the expected and obtained performance. We study the performance of the call admission control algorithm by simulation experiments. Simulation results for the adaptive frame structure algorithm show an improvement in the number of users in the system but there is a drop in the system throughput. In spite of the lower throughput the adaptive frame structure algorithm has fewer QoS delay violations. The adaptive call admission control algorithm adapts the call dropping probability of different classes of …
Date: August 2000
Creator: Kakani, Naveen Kumar
System: The UNT Digital Library
Analysis of Web Services on J2EE Application Servers (open access)

Analysis of Web Services on J2EE Application Servers

The Internet became a standard way of exchanging business data between B2B and B2C applications and with this came the need for providing various services on the web instead of just static text and images. Web services are a new type of services offered via the web that aid in the creation of globally distributed applications. Web services are enhanced e-business applications that are easier to advertise and easier to discover on the Internet because of their flexibility and uniformity. In a real life scenario it is highly difficult to decide which J2EE application server to go for when deploying a enterprise web service. This thesis analyzes the various ways by which web services can be developed & deployed. Underlying protocols and crucial issues like EAI (enterprise application integration), asynchronous messaging, Registry tModel architecture etc have been considered in this research. This paper presents a report by analyzing what various J2EE application servers provide by doing a case study and by developing applications to test functionality.
Date: May 2004
Creator: Gosu, Adarsh Kumar
System: The UNT Digital Library
Analyzing Microwave Spectra Collected by the Solar Radio Burst Locator (open access)

Analyzing Microwave Spectra Collected by the Solar Radio Burst Locator

Modern communication systems rely heavily upon microwave, radio, and other electromagnetic frequency bands as a means of providing wireless communication links. Although convenient, wireless communication is susceptible to electromagnetic interference. Solar activity causes both direct interference through electromagnetic radiation as well as indirect interference caused by charged particles interacting with Earth's magnetic field. The Solar Radio Burst Locator (SRBL) is a United States Air Force radio telescope designed to detect and locate solar microwave bursts as they occur on the Sun. By analyzing these events, the Air Force hopes to gain a better understanding of the root causes of solar interference and improve interference forecasts. This thesis presents methods of searching and analyzing events found in the previously unstudied SRBL data archive. A new web-based application aids in the searching and visualization of the data. Comparative analysis is performed amongst data collected by SRBL and several other instruments. This thesis also analyzes events across the time, intensity, and frequency domains. These analysis methods can be used to aid in the detection and understanding of solar events so as to provide improved forecasts of solar-induced electromagnetic interference.
Date: May 2007
Creator: Kincaid, Cheryl-Annette
System: The UNT Digital Library
An Annotated Bibliography of Mobile Agents in Networks (open access)

An Annotated Bibliography of Mobile Agents in Networks

The purpose of this thesis is to present a comprehensive colligation of applications of mobile agents in networks, and provide a baseline association of these systems. This work has been motivated by the fact that mobile agent systems have been deemed proficuous alternatives in system applications. Several mobile agent systems have been developed to provide scalable and cogent solutions in network-centric applications. This thesis examines some existing mobile agent systems in core networking areas, in particular, those of network and resource management, routing, and the provision of fault tolerance and security. The inherent features of these systems are discussed with respect to their specific functionalities. The applicability and efficacy of mobile agents are further considered in the specific areas mentioned above. Although an initial foray into a collation of this nature, the goal of this annotated bibliography is to provide a generic referential view of mobile agent systems in network applications.
Date: December 2002
Creator: Sriraman, Sandhya
System: The UNT Digital Library
Arithmetic Computations and Memory Management Using a Binary Tree Encoding af Natural Numbers (open access)

Arithmetic Computations and Memory Management Using a Binary Tree Encoding af Natural Numbers

Two applications of a binary tree data type based on a simple pairing function (a bijection between natural numbers and pairs of natural numbers) are explored. First, the tree is used to encode natural numbers, and algorithms that perform basic arithmetic computations are presented along with formal proofs of their correctness. Second, using this "canonical" representation as a base type, algorithms for encoding and decoding additional isomorphic data types of other mathematical constructs (sets, sequences, etc.) are also developed. An experimental application to a memory management system is constructed and explored using these isomorphic types. A practical analysis of this system's runtime complexity and space savings are provided, along with a proof of concept framework for both applications of the binary tree type, in the Java programming language.
Date: December 2011
Creator: Haraburda, David
System: The UNT Digital Library
Automated Testing of Interactive Systems (open access)

Automated Testing of Interactive Systems

Computer systems which interact with human users to collect, update or provide information are growing more complex. Additionally, users are demanding more thorough testing of all computer systems. Because of the complexity and thoroughness required, automation of interactive systems testing is desirable, especially for functional testing. Many currently available testing tools, like program proving, are impractical for testing large systems. The solution presented here is the development of an automated test system which simulates human users. This system incorporates a high-level programming language, ATLIS. ATLIS programs are compiled and interpretively executed. Programs are selected for execution by operator command, and failures are reported to the operator's console. An audit trail of all activity is provided. This solution provides improved efficiency and effectiveness over conventional testing methods.
Date: May 1977
Creator: Cartwright, Stephen C.
System: The UNT Digital Library
Automatic Speech Recognition Using Finite Inductive Sequences (open access)

Automatic Speech Recognition Using Finite Inductive Sequences

This dissertation addresses the general problem of recognition of acoustic signals which may be derived from speech, sonar, or acoustic phenomena. The specific problem of recognizing speech is the main focus of this research. The intention is to design a recognition system for a definite number of discrete words. For this purpose specifically, eight isolated words from the T1MIT database are selected. Four medium length words "greasy," "dark," "wash," and "water" are used. In addition, four short words are considered "she," "had," "in," and "all." The recognition system addresses the following issues: filtering or preprocessing, training, and decision-making. The preprocessing phase uses linear predictive coding of order 12. Following the filtering process, a vector quantization method is used to further reduce the input data and generate a finite inductive sequence of symbols representative of each input signal. The sequences generated by the vector quantization process of the same word are factored, and a single ruling or reference template is generated and stored in a codebook. This system introduces a new modeling technique which relies heavily on the basic concept that all finite sequences are finitely inductive. This technique is used in the training stage. In order to accommodate the variabilities …
Date: August 1996
Creator: Cherri, Mona Youssef, 1956-
System: The UNT Digital Library
Benchmark-based Page Replacement (BBPR) Strategy: A New Web Cache Page Replacement Strategy (open access)

Benchmark-based Page Replacement (BBPR) Strategy: A New Web Cache Page Replacement Strategy

World Wide Web caching is widely used through today's Internet. When correctly deployed, Web caching systems can lead to significant bandwidth savings, network load reduction, server load balancing, and higher content availability. A document replacement algorithm that can lower retrieval latency and yield high hit ratio is the key to the effectiveness of proxy caches. More than twenty cache algorithms have been employed in academic studies and in corporate communities as well. But there are some drawbacks in the existing replacement algorithms. To overcome these shortcomings, we developed a new page replacement strategy named as Benchmark-Based Page Replacement (BBPR) strategy, in which a HTTP benchmark is used as a tool to evaluate the current network load and the server load. By our simulation model, the BBPR strategy shows better performance than the LRU (Least Recently Used) method, which is the most commonly used algorithm. The tradeoff is a reduced hit ratio. Slow pages benefit from BBPR.
Date: May 2003
Creator: He, Wei
System: The UNT Digital Library
Building an Intelligent Filtering System Using Idea Indexing (open access)

Building an Intelligent Filtering System Using Idea Indexing

The widely used vector model maintains its popularity because of its simplicity, fast speed, and the appeal of using spatial proximity for semantic proximity. However, this model faces a disadvantage that is associated with the vagueness from keywords overlapping. Efforts have been made to improve the vector model. The research on improving document representation has been focused on four areas, namely, statistical co-occurrence of related items, forming term phrases, grouping of related words, and representing the content of documents. In this thesis, we propose the idea-indexing model to improve document representation for the filtering task in IR. The idea-indexing model matches document terms with the ideas they express and indexes the document with these ideas. This indexing scheme represents the document with its semantics instead of sets of independent terms. We show in this thesis that indexing with ideas leads to better performance.
Date: August 2003
Creator: Yang, Li
System: The UNT Digital Library
A C Navigational System (open access)

A C Navigational System

The C Navigational System (CNS) is a proposed programming environment for the C programming language. The introduction covers the major influences of programming environments and the components of a programming environment. The system is designed to support the design, coding and maintenance phases of software development. CNS provides multiple views to both the source and documentation for a programming project. User-defined and system-defined links allow the source and documentation to be hierarchically searched. CNS also creates a history list and function interface for each function in a module. The final chapter compares CNS and several other programming environments (Microscope, Rn, Cedar, PECAN, and Marvel).
Date: May 1989
Creator: Hammerquist, James D. (James Daniel)
System: The UNT Digital Library
Case-Based Reasoning for Children Story Selection in ASP.NET (open access)

Case-Based Reasoning for Children Story Selection in ASP.NET

This paper describes the general architecture and function of a Case-Based Reasoning (CBR) system implemented with ASP.NET and C#. Microsoft Visual Studio .NET and XML Web Services provide a flexible, standards-based model that allows clients to access data. Web Form Pages offer a powerful programming model for Web-enabled user interface. The system provides a variety of mechanisms and services related to story retrieval and adaptation. Users may browse and search a library of text stories. More advanced CBR capabilities were also implemented, including a multi-factor distance-calculation for matching user interests with stories in the library, recommendations on optimizing search, and adaptation of stories to match user interests.
Date: December 2003
Creator: Hu, Demin
System: The UNT Digital Library
A Comparison of Agent-Oriented Software Engineering Frameworks and Methodologies (open access)

A Comparison of Agent-Oriented Software Engineering Frameworks and Methodologies

Agent-oriented software engineering (AOSE) covers issues on developing systems with software agents. There are many techniques, mostly agent-oriented and object-oriented, ready to be chosen as building blocks to create agent-based systems. There have been several AOSE methodologies proposed intending to show engineers guidelines on how these elements are constituted in having agents achieve the overall system goals. Although these solutions are promising, most of them are designed in ad-hoc manner without truly obeying software developing life-cycle fully, as well as lacking of examinations on agent-oriented features. To address these issues, we investigated state-of-the-art techniques and AOSE methodologies. By examining them in different respects, we commented on the strength and weakness of them. Toward a formal study, a comparison framework has been set up regarding four aspects, including concepts and properties, notations and modeling techniques, process, and pragmatics. Under these criteria, we conducted the comparison in both overview and detailed level. The comparison helped us with empirical and analytical study, to inspect the issues on how an ideal agent-based system will be formed.
Date: December 2003
Creator: Lin, Chia-En
System: The UNT Digital Library
A Comparison of Meansort and Quicksort (open access)

A Comparison of Meansort and Quicksort

The main purpose of this project is to compare a new sorting method- Meansort with its preceding sorting method- Quicksort. Meansort uses the mean value for each key to determine the partition of the file, but Quicksort selects at random. Experiments proved that in some ways Meansort is superior to Quicksort but is still not perfect since it always needs a mean value for each key. This project implements these two methods and determines the situations under which each of these methods outperforms the other.
Date: November 1985
Creator: Tsang, Pey Betty
System: The UNT Digital Library
Computational Complexity of Hopfield Networks (open access)

Computational Complexity of Hopfield Networks

There are three main results in this dissertation. They are PLS-completeness of discrete Hopfield network convergence with eight different restrictions, (degree 3, bipartite and degree 3, 8-neighbor mesh, dual of the knight's graph, hypercube, butterfly, cube-connected cycles and shuffle-exchange), exponential convergence behavior of discrete Hopfield network, and simulation of Turing machines by discrete Hopfield Network.
Date: August 1998
Creator: Tseng, Hung-Li
System: The UNT Digital Library
A Computer Algorithm for Synthetic Seismograms (open access)

A Computer Algorithm for Synthetic Seismograms

Synthetic seismograms are a computer-generated aid in the search for hydrocarbons. Heretofore the solution has been done by z-transforms. This thesis presents a solution based on the method of finite differences. The resulting algorithm is fast and compact. The method is applied to three variations of the problem, all three are reduced to the same approximating equation, which is shown to be optimal, in that grid refinement does not change it. Two types of algorithms are derived from the equation. The number of obvious multiplications, additions and subtractions of each is analyzed. Critical section of each requires one multiplication, two additions and two subtractions. Four sample synthetic seismograms are shown. Implementation of the new algorithm runs twice as fast as previous computer program.
Date: August 1977
Creator: Isaacson, James
System: The UNT Digital Library
Computer Graphics Primitives and the Scan-Line Algorithm (open access)

Computer Graphics Primitives and the Scan-Line Algorithm

This paper presents the scan-line algorithm which has been implemented on the Lisp Machine. The scan-line algorithm resides beneath a library of primitive software routines which draw more fundamental objects: lines, triangles and rectangles. This routine, implemented in microcode, applies the A(BC)*D approach to word boundary alignments in order to create an extremely fast, efficient, and general purpose drawing primitive. The scan-line algorithm improves on previous methodologies by limiting the number of CPU intensive instructions and by minimizing the number of words referenced. This paper will describe how to draw scan-lines and the constraints imposed upon the scan-line algorithm by the Lisp Machine's hardware and software.
Date: December 1988
Creator: Myjak, Michael D. (Michael David)
System: The UNT Digital Library
Computer Realization of Human Music Cognition (open access)

Computer Realization of Human Music Cognition

This study models the human process of music cognition on the digital computer. The definition of music cognition is derived from the work in music cognition done by the researchers Carol Krumhansl and Edward Kessler, and by Mari Jones, as well as from the music theories of Heinrich Schenker. The computer implementation functions in three stages. First, it translates a musical "performance" in the form of MIDI (Musical Instrument Digital Interface) messages into LISP structures. Second, the various parameters of the performance are examined separately a la Jones's joint accent structure, quantified according to psychological findings, and adjusted to a common scale. The findings of Krumhansl and Kessler are used to evaluate the consonance of each note with respect to the key of the piece and with respect to the immediately sounding harmony. This process yields a multidimensional set of points, each of which is a cognitive evaluation of a single musical event within the context of the piece of music within which it occurred. This set of points forms a metric space in multi-dimensional Euclidean space. The third phase of the analysis maps the set of points into a topology-preserving data structure for a Schenkerian-like middleground structural analysis. This …
Date: August 1988
Creator: Albright, Larry E. (Larry Eugene)
System: The UNT Digital Library
Content-Based Image Retrieval by Integration of Metadata Encoded Multimedia Features in Constructing a Video Summarizer Application. (open access)

Content-Based Image Retrieval by Integration of Metadata Encoded Multimedia Features in Constructing a Video Summarizer Application.

Content-based image retrieval (CBIR) is the retrieval of images from a collection by means of internal feature measures of the information content of the images. In CBIR systems, text media is usually used only to retrieve exemplar images for further searching by image feature content. This research work describes a new method for integrating multimedia text and image content features to increase the retrieval performance of the system. I am exploring the content-based features of an image extracted from a video to build a storyboard for search retrieval of images. Metadata encoded multimedia features include extracting primitive features like color, shape and text from an image. Histograms are built for all the features extracted and stored in a database. Images are searched based on comparing these histogram values of the extracted image with the stored values. These histogram values are used for extraction of keyframes from a collection of images parsed from a video file. Individual shots of images are extracted from a video clip and run through processes that extract the features and build the histogram values. A keyframe extraction algorithm is run to get the keyframes from the collection of images to build a storyboard of images. In …
Date: May 2003
Creator: Anusuri, Ramprasad
System: The UNT Digital Library
Control Mechanisms and Recovery Techniques for Real-Time Data Transmission Over the Internet. (open access)

Control Mechanisms and Recovery Techniques for Real-Time Data Transmission Over the Internet.

Streaming multimedia content with UDP has become popular over distributed systems such as an Internet. This may encounter many losses due to dropped packets or late arrivals at destination since UDP can only provide best effort delivery. Even UDP doesn't have any self-recovery mechanism from congestion collapse or bursty loss to inform sender of the data to adjust future transmission rate of data like in TCP. So there is a need to incorporate various control schemes like forward error control, interleaving, and congestion control and error concealment into real-time transmission to prevent from effect of losses. Loss can be repaired by retransmission if roundtrip delay is allowed, otherwise error concealment techniques will be used based on the type and amount of loss. This paper implements the interleaving technique with packet spacing of varying interleaver block size for protecting real-time data from loss and its effect during transformation across the Internet. The packets are interleaved and maintain some time gap between two consecutive packets before being transmitted into the Internet. Thus loss of packets can be reduced from congestion and preventing loss of consecutive packets of information when a burst of several packets are lost. Several experiments have been conducted with …
Date: August 2002
Creator: Battula, Venkata Krishna Rao
System: The UNT Digital Library
Convexity-Preserving Scattered Data Interpolation (open access)

Convexity-Preserving Scattered Data Interpolation

Surface fitting methods play an important role in many scientific fields as well as in computer aided geometric design. The problem treated here is that of constructing a smooth surface that interpolates data values associated with scattered nodes in the plane. The data is said to be convex if there exists a convex interpolant. The problem of convexity-preserving interpolation is to determine if the data is convex, and construct a convex interpolant if it exists.
Date: December 1995
Creator: Leung, Nim Keung
System: The UNT Digital Library
DADS - A Distributed Agent Delivery System (open access)

DADS - A Distributed Agent Delivery System

Mobile agents require an appropriate platform that can facilitate their migration and execution. In particular, the design and implementation of such a system must balance several factors that will ensure that its constituent agents are executed without problems. Besides the basic requirements of migration and execution, an agent system must also provide mechanisms to ensure the security and survivability of an agent when it migrates between hosts. In addition, the system should be simple enough to facilitate its widespread use across large scale networks (i.e Internet). To address these issues, this thesis discusses the design and implementation of the Distributed Agent Delivery System (DADS). The DADS provides a de-coupled design that separates agent acceptance from agent execution. Using functional modules, the DADS provides services ranging from language execution and security to fault-tolerance and compression. Modules allow the administrator(s) of hosts to declare, at run-time, the services that they want to provide. Since each administrative domain is different, the DADS provides a platform that can be adapted to exchange heterogeneous blends of agents across large scale networks.
Date: December 2002
Creator: Cozzolino, Clifford Joseph
System: The UNT Digital Library